Gel-forming fibres such as alginate fibres and carboxymethylated cellulose fibres are known. Wound dressings of various constructions containing such fibres have been marketed. Treatment of cavity wounds, including the use of dressings, is discussed by C P Berry in an article entitled “Cavity wound management” in J. Wound Care, 1993, vol. 2, no. 1, pp. 29-32 and by A Hallett in an article entitled “Cavity-Wound Management” in Nursing Times, 1995, vol. 91, no. 30, pp. 72, 74 and 79. Dressings for packing cavity wounds are desirably flexible and conformable and capable of removal in one piece after use, without trauma to the patient and without leaving residual fragments of the dressing in the wound. Alginate cavity wound dressings are recommended for moderately and heavily exuding wounds. Such dressings are commonly in the form of a textile sliver and consequently have low mechanical strength and integrity.
Needled nonwoven fabrics (needle-tacked or needle-punched fabrics, needlefelts) of alginate staple fibres have been marketed as wound dressings. Alginate fibres are weak fibres, particularly when wetted, and accordingly a balance must be struck between conflicting desires for mechanical strength and integrity (requiring high-intensity needling and/or high basis weight fabric) and for suppleness (reduced by high-intensity needling and/or the use of high basis weight fabric). If a dressing has poor mechanical strength, a secondary (backing) dressing may be employed; but this is time-consuming and adds extra work and cost when the dressing is applied. Also, use of such secondary dressings is undesirable or inappropriate with dressings for cavity wounds. Alginate dressings having a backing layer affixed with adhesive are known, but they are unsuited for applications such as the treatment of cavity wounds.
WO-A-89/12471 discloses a pad of alginate fibres which have first and second cations (e.g. calcium sodium alginate) and the wetting of such pads prior to their use as wound dressings. The pad may be a needle-punched nonwoven fabric of staple fibre.
EP-A-0,344,913 discloses a hydroentangled fabric of alginate staple fibres and the use thereof as a wound dressing. At low basis weights (less than about 20 or 50 g/m2), the fabric preferably includes a small percentage of reinforcing fibre such as rayon to permit it to be handled easily while saturated with saline water.
EP-A-0,476,576 discloses a nonwoven fabric of alginate staple fibres made by a modified needle-tacking process, in which the leading barb of the needles penetrates into a mat of fibres to a depth of from about 60 to about 99% of the thickness of the mat. These fabrics are said to find use as wound dressings.
U.S. Pat. No. 5,674,524 discloses an alginate dressing having an integral non-alginate backing layer. A web of alginate staple fibre and a backing layer are brought together and needle-punched to yield a composite dressing. Examples are given of a fibrous backing layer which is an acrylic/cotton continuous backing or is an elastic polyurethane foam.